Historically, the monitoring of water quality in water transmission and distribution systems has been done through the discrete sampling of particular sites of interest and at random intervals. The samples collected are usually processed off-line through wet-chemistry methods. The processing often takes place several days or weeks after the sample has been gathered. Accordingly, there may be some instances where the degradation in the water quality is only apparent after the change in water quality has caused human illness and/or environmental changes.
Within the last few years, breakthroughs in sensor technology have largely shortened the time required for measurement of the various parameters that dictate the quality of a fluid such as water. The required time for the measurement of such parameters has been reduced into minutes or seconds. Furthermore, the measurement of multiple parameters has been integrated into portable sensor modules. The rapidly maturing technologies in the areas of telecommunication and Internet systems also provide long-distance telemetry solutions for the online monitoring of the quality of water in a water distribution network.
However, there exist several problems with the presently used sensors. Water distribution monitoring networks typically comprise a host station and remote sensors. Electrical power is required for the remote sensors so that they can perform functions like sensing, signal conditioning, data logging and data transmission towards the host station. In reality, the location of water distribution networks and their respective pipe lines are not always close to electricity supply networks. In such cases, the remote sensors have to be self-powered. Some known methods for powering up the remote sensors include using batteries and solar cells. The drawbacks of these power sources are that the batteries need to be recharged or replaced due to their very limited lifespan and solar cells can only work properly under restricted environmental and weather conditions.
As for methods of data transmission between the host terminal and remote sensors, said methods include cellular telephone, GPS satellite, Internet or intranet. For all these methods, the remote sensor must be equipped with a modem and/or an antenna, which means, the remote sensor has to be exposed to the elements as it may include an on-surface module, that is, a module provided on the outer surface of a pipe. The drawback here is that such an on-surface module needs to be protected and regularly surveilled, which then introduces significant manpower costs for the monitoring of water distribution networks having large numbers of remote sensors.
The present invention seeks to overcome the aforesaid problems and difficulties. It is therefore an object of the present invention to provide a fluid sensor having improved reliability and lifespan and which is easy and cheap to operate.